Heya! Coming from StampTutorial And the measures given aren't correct for you?? I'm here to help you with that!
I will list the measures needed for both resizing and placing the base/template on top of the image without "stray pixels" n whatnot. ^3^
For overlay section, ALWAYS EXTEND CANVAS SIZE!!!!!!!! OR IT WILL LOOK LIKE THIS: 
This is an ABSOLUTE WIP. and also i make mistakes . if i noticed i #fuckedup ill fix it as fast as i can 
ogh... and also i reccomend using desktop mode for this. it looks terrible otherwise.
Okay so this page is SLIGHTLY outdated because adding the overlay may make the stamp template smaller(or bigger) than it's actually supposed to be!!! :C 
If things don't look right, try to make the size  of the template slightly bigger than  the size of the resize!!!! (In "Overlay Size")
 "BASE.PNG" - RESIZE; WIDTH 97 HEIGHT  51 - OVERLAY; LEFT 47 TOP 23 - OVERLAY SIZE; - WITDH 100 HEIGHT 56-57 

 "stamp_template_tumblr_border_99x56.png" - RESIZE; WIDTH 97 HEIGHT  56 - OVERLAY; LEFT 46 TOP 28
 "stamp_template_tumblr_border_99x56.png" - RESIZE; WIDTH 97 HEIGHT  56 - OVERLAY; LEFT 46 TOP 28 
 "stamp_template_windows95.png" - RESIZE; WIDTH 92 HEIGHT 45 - OVERLAY; LEFT 42 TOP 11
 "stamp_template_windows95.png" - RESIZE; WIDTH 92 HEIGHT 45 - OVERLAY; LEFT 42 TOP 11 
 "stamp_template_windows95_2.png - RESIZE; WIDTH 92 HEIGHT  45 - OVERLAY; LEFT 42 TOP 11
 "stamp_template_windows95_2.png - RESIZE; WIDTH 92 HEIGHT  45 - OVERLAY; LEFT 42 TOP 11 
 + Karas' Recolors "stamp_template_basic.png" - RESIZE; WIDTH 91  HEIGHT 47 - OVERLAY; LEFT 40 TOP 18
 + Karas' Recolors "stamp_template_basic.png" - RESIZE; WIDTH 91  HEIGHT 47 - OVERLAY; LEFT 40 TOP 18  